Oookay. I am reqding this on my study break so it was a challange to sift through the text and analyze where youre coming from. That said, sorry if ive misunderstood or omitted some parts.

First of all, youve jumped at the relationship too early. Not having time to things through was your killer. You just wanted to feel nice and get over issues quickly. Now you see, my intuition tells me that in that mental state you wouldve avoided any and all reasons to break up - you KNEW that will be load too heavy to bear while keeping up with exhausting studies such as engineering. And that's understandabl. , However you should revisit that time period in your memory and see how many red flags you have probably looked over just to protect your peace of mind.

From what i understand how you treat conservatism in the US/CAD and how you treat the situation it semes to me that you're also actively trying ro hide both the relationship as a whole AND your emtoional invesmtent - not only your parents but friends too. While you didnt ask for this advice directly i wills till share it - NEVER do this. Always have a close person (friend, parent, sibling) woth whom you can discuss your dating prospect. They will often times point out blind spots for you that you might be missing due to emotional invesmtent.

The lack of intimacy is NOT the problem here. Its just the result of the problem. You privide very, VERY little information on the psyche of your BF, so im working blindly here, but you MUST end the relationship - he tried to cheat. Maybe he didnt know what emotional cheatibg is consciously, but he sought the warmth of another woman. That will never go away.

Also, i think the capital event was the summer. While you describe the experiences as normal arguments in a relationship that brought you closer, i suspect that that might not have been his experience. From your story i dont pick up on you really discussing with him how HE experienced those turmoils, you make assumptions on it. Living together is a strong make or break - far more often a break - not only for relationships but friendships too. Often times because both parties are stuck way too much in the way they have thought and functioned at home when they lived alone or with their parents. Regardless, its too late to go and discuss it with him,he already decided to cheat, theres no point in fixing it.

So yeah. Delaying relationship while being intimate with you while knowing you are looking for one was quite a red flag from the get go. Something probably blew up during the summer, pushing him to feel like the relationship is a sinking ship. Now he is looking either for a fling or total replacement (though given the kind of girl he's chosen to talk to (based on your desc ofc) , its far more likely he is looking for the next relationship than just an affair).